1. Field of the Invention
This invention relates to an improved automatic disk exchange device in which a large number of disks are stores in a disk storage device, one of the selected disks is automatically taken out of the storage space by a transport mechanism when required and transferred and attached to a recording/reproducing device for recording and/or reproducing the information, and in which the disk thus attached to the recording/reproducing device is again transported therefrom for storage to the disk storage device.
2. Description of the Prior Art
The automatic disk exchange device of the type described above is disclosed for example in the Japanese Patent Provisional Publication No. 24 3865/1985 and illustrated in FIG. 3 as a well-known automatic disk exchange device.
In this figure, the reference numeral 1 denotes a disk contained in a square sheet-like cassette hereinafter referred to simply as a disk, the reference numeral 2 a disk storage device in the form of a bookcase for storing the disks 1 in the upright position, the reference numeral 3 a recording/reproducing device, the reference numeral 4 a transport device disposed at the backside of the storage device 2, and the reference numeral 5 a transport frame provided to the transport device 4 and having a built-in transfer means adapted for transferring the disk 1.
In operation, when a selected one of the disks 1 in the storage device 2 is attached to the recording/reproducing device 3, the transport device 4 is driven into operation for shifting the transport frame 5 to a position facing to the selected disk 1 stored in the storage device 2 both transversely or along the x-axis and vertically or along the z-axis. When the transport frame 5 reaches a predetermined position, the transverse transfer unit transfers the disk out of the storage device 2 into the transport frame 5. The transport frame is then turned 90.degree. and moved downward to the position of the recording/reproducing unit 3. The transfer unit is then driven in the reverse direction for transporting the disk 1 by way of an inlet/outlet port 6 into the inside of the recording/reproducing unit 3. When the disk 1 has been transported into and attached in position within the recording/reproducing unit 3, the recording/reproducing device is ready to start the recording/reproducing operation.
When the operation of recording the information on or reproducing the information from the disk 1 by the device 3 is terminated, the disk 1 is transported and returned to the original storage device by the operation reverse to what is described above.
In the prior-art method, as described above, there is employed a system of a construction in which the disks are housed in the upright position in the storage device 2 in the form of a bookcase and in which the recording/reproducing device provided with the horizontally extending inlet/outlet port disposed under the storage device 2.
Such a construction has, however, the following drawbacks (i) to (iv):
(i) The operation of taking a disk out of the storage device and attaching it in position in the recording/reproducing device is time-consuming. That is, the disk transport operation usually takes three to four seconds, while the disk position changing operation usually takes about one second, such that the total disk access time is four to five seconds. If the disk is housed at a position in the storage device remote from the recording/reproducing device, the transport time is correspondingly increased.
(ii) The transport device including the transfer unit performs a three-dimensional motion, to which a rotary motion is added to effect the position changing of the disk, so that the structure is complicated and naturally susceptible to troubles.
(iii) The disk storage space efficiency is low and the overall construction tends to be increased in size.
(iv) The transport frame is supported at one point by a rotary shaft in a cantilevered fashion and increased in weight because of the built-in transfer means, thus necessitating the weight counterbalancing means such as two springs as shown. In addition, a large-sized electric motor capable of developing a larger output needs to be provided as a driving source.
This results in a more complicated structure of the overall construction with the increased rate of trouble occurrence and the increased production costs.